CreateEventDialog gains a collapsible "Buyer notifications" section
exposing the EventExtra fields added upstream in v1.4.0 / v1.6.0:
- email_notifications + nostr_notifications switches — opt buyers
into email and NIP-04 Nostr DM ticket confirmations.
- notification_subject + notification_body inputs — let organizers
customize the message. Empty falls back to extension defaults.
Submit handler builds `extra` by overlaying onto the existing
event.extra so unrelated fields the LNbits admin UI sets
(promo_codes, conditional, min_tickets) survive the round-trip
through the webapp. Populate-from-event mirrors the same.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
